X-ray Diffraction in the 25 T Florida Split Coil Magnet at the National High Magnetic Field Laboratory (NHMFL)

A novel x-ray diffraction system is under construction at the 25T Florida split coil magnet at the DC Field Facility of NHMFL, Tallahassee, FL. The purpose of the system is to probe spin-lattice coupling and crystal structure transitions as observed in various metamagnetic, magnetocaloric, multiferroic, and magnetostrictive materials. The project builds upon the proof-of-concept study at NHMFL by Wang, et al (Rev Sci Instrum 86, 123902, 2015) and fills a niche among applied field diffraction systems for the following reasons. First, high-field diffraction is made possible with small sample sizes compared to the large sample sizes needed for neutron diffraction. Second, high-field diffraction is made possible for materials with inherent difficulties in pulse fields (sample heating, etc). In addition to the 25T split coil magnet, the primary elements of the system consist of a Mo rotating anode x-ray source and a PILATUS 300K-W X hybrid pixel array detector customized to tolerate the fringe field of the split coil magnet. The challenges of XRD in a magnetic field, the strategies to overcome them, and the ongoing evolution of the system are discussed. A preliminary study of metamagnetic materials is presented with emphasis on the role of high-field XRD in the investigation.